1. Field of the Invention
At least one embodiment of the present invention relates generally to control of a converter, and more specifically, to control of a converter associated with at least one of an uninterruptable power supply, a frequency converter, and a line conditioner.
2. Background of the Invention
Converters that form at least part of uninterruptible power supplies (UPS), frequency converters, or line conditioners are used to provide reliable power to many different types of electronic equipment. Often, this electronic equipment requires particular voltage and/or current input from a converter. Unwanted distortion in converter input current can pass through to converter output and be applied to electrical equipment, which results in inefficient operation, a loss of productivity, and can require costly repair or replacement of electrical components.
FIG. 1 provides a block diagram of a typical converter 100 that forms part of a UPS that provides regulated power as well as back-up power to a load 140. UPS's similar to that shown in FIG. 1 are available from American Power Conversion (APC) Corporation of West Kingston, RI. Converter 100 can include rectifier 110, inverter 120, controller 130 and battery 150. Converter 100 has inputs 112 and 114 to couple respectively to line and neutral of an input AC power source and has outputs 116 and 118 to provide an output line and neutral to load 140.
In line mode of operation, under control of controller 130, rectifier 110 receives the input AC voltage and provides positive and negative output DC voltages at output lines 121 and 122 with respect to common line 124. In battery mode of operation, upon loss of input AC power, rectifier 110 generates DC voltages from battery 150. Common line 124 may be coupled to input neutral 114 and output neutral 118 to provide a continuous neutral through converter 100. Inverter 120 receives the DC voltages from rectifier 110 and provides an output AC voltage at lines 116 and 118.